I had a look in my parents' home pharmacy and found two glass thermometers!
One of them was a bit like this one, with different background colors for temperatures above and below 37°C (considered the normal temperature)
https://en.zity.biz/gallery/image/263997
The other one had just one single background color, like this one
https://en.zity.biz/gallery/image/263996
Both were European style, with a thin probe and a thicker body, and they were used only rectally. Both contain a blue liquid.
I have a faint recollection of using a thermometer with a red liquid, but perhaps it was at grandparents'?
Also a faint recollection that my parents used to have a mercury thermometer. Perhaps it was disposed of as hazardous waste.
Of course, it would be very awkward to ask now!